Obviously not, as I understand it, those formula should work whith _any_ angle?

It is saying there 'The method presented here does not require any alignment with gravity'

That moment is somewhat unclear to me.

What actually means 'axis of sensitivity'? Sensor has 3 axis, and it seems that none of them is required to be aligned with gravity, .

Can you please explain it in more details?

Oh, I am starting to understand. Rotation effectively eliminates misalignment in vertical plane only,

or, rather, in a plane orthogonal to rotation axis

So to make it work for any angle, I must mount it on a cube and take 12 readings.

Thanks for a hint, johnwasser!